tmetro@pro-angmar.UUCP (Tom Metro) (04/20/88)
I read an article that explained how you could copy the ROM code at $D000 to $F800 into the Bank Switched RAM on a //e. This then allowed you to modify vectors that are at the top of the address space, such as RESET, IRQ and NMI. I tried this on my //c. I was able to copy the ROM code, verify that I had copied it, modify the code, and verify my modifications. The modification I tried was to redirect the RESET vector, but it wouldn't work. I verified that I had the Bank Switched RAM selected for read operations by looking at the status of $C011 and $C012. The RESET still caused a normal reset and left the //c with the ROMs selected and the RAM turned off. Does anyone know if the hardware that controls the bank switching on a //c gets reset with the RESET signal? It must not on a //e for this to work... Is the $D000-$FFFF bank switched RAM contained on the motherboard of the //e? This article gave me the impression that it was located on a card, but maybe that refers to an unenhanced //e. Thanks.
kamath@reed.UUCP (Sean Kamath) (04/26/88)
In article <8804200757.AA17542@crash.cts.com> pnet01!pro-angmar!tmetro@nosc.MIL writes: > > [stuff on resets on a //e] >Does anyone know if the hardware that controls the bank switching on a //c >gets reset with the RESET signal? >It must not on a //e for this to work... >Is the $D000-$FFFF bank switched RAM contained on the motherboard of the //e? >This article gave me the impression that it was located on a card, but maybe >that refers to an unenhanced //e. > >Thanks. Well, I'm not sure about this. . . Ican dig it up, if anyone cares. BUT: on a //c, it "knows" that no card with ROM will be in slot 3. On a //e, this is not the case. From what I recall, you *may* be able to do what you want on a //e, maybe when I log off I'll try it. BUT: Not on a //c. Since the //c generally has a fixed set of slots, it's interrupts are vectored straight tothe 80 column firmware. Note that on a //e, having the 80column card does not mean anything in the way of the firmware. The firmware is on the motherboard. Unfortunately, I cannot give a very good discription of the interrupts on the //e right now. I left my ref. manual at the ski cabin, and haven' been able to go there for two months. . . I've made do with the //c one, but it is different in a few respects, and this is one of them. . . Sean Kamath -- UUCP: {decvax allegra ucbcad ucbvax hplabs ihnp4}!tektronix!reed!kamath CSNET: reed!kamath@Tektronix.CSNET || BITNET: reed!kamath@PSUVAX1.BITNET ARPA: reed!kamath@psuvax1.arpa US Snail: 3934 SE Boise, Portland, OR 97202-3126 (I hate 4 line .sigs!)